Underwater sound transducers are devices that detect or generate and radiate sound in water to determine the location of objects in the water or for purposes of communication. The transducer converts electric energy into acoustic energy or acoustic energy into electrical energy.
One type of transducer utilized by the prior art is a flextensional transducer. Flextensional transducers have wider bandwidths, lower operating frequencies and higher power handling capabilities than other types of transducers of comparable size. A flextensional transducer has a flexible outer shell or housing which is excited by a piezoelectric or piezomagnetic transducer stack or driving element that is driven in a length expander mode. The stack is placed in compression between opposing interior walls of the shell. The elongation and contraction of the stack imparts a motion to the shell which, in general, radiates or couples energy into the water.
As submarines become quieter and the background noises of the ocean increase due to increased commerce, it becomes more and more difficult to locate foreign submarines by means of passive detection. One means to detect quieter running submarines in a noisier environment is to use active sonar systems (projectors and receivers). In most applications to construct the transducer so that it will be as small as possible, i.e., in an active towed array the transducer should be small and light in weight so that it will have low drag and not sink and array. Thus, it is apparent that there is a need for a smaller, lighter in weight, more efficient underwater sound transducer that may be used at very low frequencies.